AGRICULTURAL EXPERIMENT STATION. 91 



growth. Consequently, certain cattle foods, bj' being much more 

 digestible than others, are much more completely utilized. 



The main facts of digestion, and those upon which the methods 

 of digestion experiments are based, are the following : A portion 

 of the food which an animal eats is dissolved by the several 

 digestive fluids with which it comes in contact, viz., the saliva, 

 gastric juice, pancreatic juice, etc. That which is dissolved, or 

 digested, is absorbed by certain vessels which are distributed over 

 the lining of the stomach and intestines, passes into the blood, and 

 is then used to maintain and build up the animal body. The 

 undissolved or undigested portion of the food is carried along the 

 alimentary canal, passes from the body as the feces or dung, and 

 constitutes that part of the food which is useless for the purposes 

 of the nutrition. The method of ascertaining the digestibility of 

 any cattle food is simple in principle. An animal is fed a weighed 

 quantity of food, of which the composition is determined by analysis. 

 The solid excrement is collected, weighed and analyzed, and the 

 amount digested is the difference between that which is fed and that 

 which is excreted. From the data thus obtained is calculated the 

 percentage that is digested of each- ingredient, these several per- 

 centages being called the coefficients of digestibility. As the process 

 of digestion is slow, it is necessary to feed the animal on the weighed 

 ration several days before collecting any excrement, in order that 

 the contents of the intestines may become whollj^ freed from the 

 residue of the previous food, so that the dung collected shall come 

 wholly from the food tested. On account of the irregularity with 

 which dung is voided, it is collected for several days, and from the 

 total amount the average for one da}' is calculated. 



The digestibilit}' of these fodders was studied through digestion 

 experiments with sheep and by treating them with artificial solutions 

 of pepsin and paucreas. 



EXPERIMENTS WITH SHEEP. 



In the digestion experiments with sheep the animals used were 

 full grown wethers in all cases. The}' were confined during the 

 time the experimental rations were fed, in stalls large enough to 

 allow comfortable lying down, but small enough to oblige the 

 animal to feed in such a wa}' as to prevent loss. The feed boxes 

 were zinc lined, and projected up around the head in front and at 

 the sides so that none of the finely cut fodder could easily be 

 scattered out. The feces was collected in rubber lined bags closely 



